1. Heterogeneous Networking for Future Wireless Broadband Networks
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IEEE C /0003r1
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Nageen Himayat, Shilpa Talwar, Kerstin Johnsson,
Kamran Etemad, Jose Puthenkulum, Vivek Gupta, Lily Yang, Minyoung Park, Geng Wu, Caroline Chan, Intel Corporation
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San Diego, CA, USA
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For discussion in the Project Planning Adhoc
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2. Heterogeneous Networking for Future Wireless Broadband Networks Input for 802-wide Tutorial in March

3. Agenda Motivation Challenges and Current Approaches
Preliminary Requirements
Summary & Recommendations 3

4. Heterogeneous Networks
Exploit multiple radio interfaces at network or client
Ex: Co-located WiFi/WiMAX interfaces in operator controlled femto-cell networks
Utilize licensed and unlicensed spectrum
Virtual WiMAX carrier available through WiFi
Multi-network access possible for single-radio client
Improve throughput by 2-3x in addition to coverage and QoS
WiMAX/WiFi Mobile
Internet Device
WiMAX
Integrated WiFi/ WiMax
Femtocell
Simultaneous
Multi -
radio Operation
WiFi
WAN
Mobile Hotspot
MyFi
radio device
Virtual Carrier (WiFi) 4

5. Heterogeneous Networks Deployment Scenarios
Hotspot
Multi-radio
Smart-Phone
Home
Integrated Femto-AP
Integrated
Pico-cell
Enterprise
Mobile Hotspot
Laptop w/
WiFi & WiMAX
Multi-radio
Device
Laptop w/
WiFi & WiMAX
Integrated
Femto-AP 5

6. Heterogeneous Network Techniques
Idea
Enhanced Interworking Techniques
Description
Target Gains
Virtual WiMAX carrier
Interference Avoidance
Dynamically switch between WiFi & WiMAX to avoid interference
Increases system throughput ~3x
Diversity/Redundancy Transmission
Use added spectrum to improve diversity, code rates with incremental redundancy
Increases SINR ~3-5 dB, decreases cell-edge outage
Carrier Aggregation
Use added spectrum to transmit independent data streams
Increases peak throughput ~2-3x
QoS/ Load Balancing
QoS-aware mapping of apps to different spectrum
Improves QoS, system capacity
Energy Efficiency
Use virtual carrier to lower overall transmit power
Improved energy efficiency
Reduced Overhead w/ Unified Control
Streamline access, paging, other control procedures across networks
Improves power consumption, overhead
Multi- network access
Routing/Access
Provide connectivity between heterogeneous protocols
Improves connectivity, coverage 6

7. Advantages of Heterogeneous Networks: Summary
User
Improved cell capacity (> 2x)
Improved cell-edge rates (> 2x)
Reduced Overhead
Lower deployment costs (TBD)
Higher Peak Rates (>2 x)
Improved QoS (TBD)
Reduced distortion for video (TBD)
Power savings (TBD)

8. Heterogeneous Network Challenges
Multi-radio protocols & interfaces required
Define Generic Link Layer (GLL) *
Manage interworking between heterogeneous links
Define Multi-Radio Resource Management (MRRM) *
Manage radio resources across heterogeneous links
Determine depth of interworking across the protocol stack
Example: spectrum aggregation
Available in WiMAX & WiFi currently
WiFi channel bonding at PHY layer w/ MAC coordination
WiMAX carrier aggregation at MAC layer
Example: WiFi Off-load
3GPP considering IP layer interworking between WiFi & LTE
GLL
WLAN
WiMAX
OTHER
MRRM
Network (AP/BS)
Multi-Radio Client
* FP6: Ambient Network Framework
Develop integrated multi-radio protocol design for /11 8

9. Example: Channel Bonding in 802.11n
PHY layer bonding of adjacent 20 MHZ channels for 40 MHz channel
Single FFT across 40 MHz
MAC layer coordination for 40 MHz channel access
Enhancements in 11ac, to support 80 MHz channels
Wait for PIFS < DIFS for secondary channel clear channel assessment (priority access)
802.11n Contention Based MAC

10. Example: Carrier Aggregation in 802.16m
Aggregate N “fully” or “partially” configured “non-contiguous” carriers
MAC layer aggregation, w/ dynamic scheduling across carriers
Designate “Primary” carrier for main control interface
Restricted PHY layer segmentation (for contiguous bands)

11. Example: WiFi-Offload Discussion in 3GPP
3GPP considering “IP flow mobility and seamless WLAN offload,” (TS )
Simultaneous connectivity across multiple access systems (3GPP, WLAN) with multi-mode devices.
Aggregation at IP layer
Multiple IP flows to a user can be routed through different access networks (3GPP or WLAN) based on operator control
Mobility support: only selected IP flows may be handed off

12. Tradeoffs in Integrating Multi-radio Protocols
Attribute
PHY Layer Integration
MAC Layer Integration
IP Layer Integration
Track dynamic link variations
Yes
Average link variations only
Suitable Techniques
PHY layer combining, channel coding, MAC layer scheduling
MAC layer scheduling, Interference avoidance
QoS-aware mapping, Load Balancing
Synchronization
Tight Synchronization
Reduced Synchronization
Minimal Synchronization
Control Overhead Reduction
Reduced
Limited Reduction
Flexible Spectrum Usage
Contiguous spectrum required
Flexible
Co-location Requirement
Co-located interfaces required
Flexible mapping across distributed air interfaces 12

13. Requirements to Enable Virtual Carrier
Aggregate “N” licensed and “M” un-licensed non-contiguous carriers (e.g. WiFi & WiMAX)
Enable tighter interworking for co-located interfaces (WiFi & WiMAX)
Allow for dynamic channel tracking
Minimize changes to existing protocol stacks
Enable information exchange across protocol stacks
Minimize control interfaces, and designate an “Anchor” protocol
Design extensible protocols for distributed scenarios

14. Summary & Recommendations
Heterogeneous networking techniques for WiFi & WiMAX promise significant improvements in network throughput and user QoS
Next generation standard should develop protocols to synergistically enable use of additional un-licensed WiFi carriers